futexes: Still infinite loop in get_futex_key() in 2.6.31-rc4

Jens Rosenboom
2009-07-27T08:00:49Z

We have a problem with infinitely running processes on kernels at least
since 2.6.29.4. It happens on a loaded machine after running for a
couple of days, that a "ps ax" seems to get stuck in get_futex_key while
exiting. Sadly your patch does not fix it as I hoped from the
description, maybe the following tracebacks taken a couple of minutes
apart from the same process can help in identifying some further bug
here:

ps R running 0 12886 12884 0x00000000
c9189cc4 c136ea4b 03d5e000 00000058 c9189c68 c1053959 00000000 c40d6e00
0000061e c9189cb4 c104b558 fffff000 00000007 c1b18000 80000000 c9189d18
00000000 c9189c9c c1020e3f 00000163 80000000 b7f1c000 c9189cc0 c1020135
Call Trace:
[<c136ea4b>] ? schedule+0x28b/0x970
[<c1057bce>] ? trace_hardirqs_on_caller+0x5e/0x180
[<c1020e3f>] ? kmap_atomic+0x1f/0x30
[<c1020135>] ? gup_pte_range+0x115/0x190
[<c1020252>] ? gup_pud_range+0xa2/0x120
[<c1020405>] ? get_user_pages_fast+0x135/0x170
[<c1057cfb>] ? trace_hardirqs_on+0xb/0x10
[<c1020405>] ? get_user_pages_fast+0x135/0x170
[<c105bed5>] ? get_futex_key+0x95/0x1c0
[<c105c60c>] ? futex_wake+0x4c/0x110
[<c105de0d>] ? do_futex+0x21d/0xd00
[<c101bd86>] ? no_context+0x26/0x1a0
[<c102a013>] ? finish_task_switch+0x33/0xf0
[<c101bfbb>] ? __bad_area_nosemaphore+0xbb/0x180
[<c1058d8d>] ? __lock_acquire+0x39d/0x18e0
[<c1058d8d>] ? __lock_acquire+0x39d/0x18e0
[<c101c0c9>] ? __bad_area+0x29/0x50
[<c101c0da>] ? __bad_area+0x3a/0x50
[<c101c122>] ? bad_area_access_error+0x12/0x20
[<c1002e1c>] ? restore_all_notrace+0x0/0x18
[<c101c210>] ? do_page_fault+0x0/0x280
[<c1057c9c>] ? trace_hardirqs_on_caller+0x12c/0x180
[<c105e992>] ? sys_futex+0xa2/0x130
[<c101c210>] ? do_page_fault+0x0/0x280
[<c102fa68>] ? mm_release+0xa8/0xc0
[<c1033668>] ? exit_mm+0x18/0x110
[<c1065121>] ? acct_collect+0x131/0x180
[<c10353cb>] ? do_exit+0x60b/0x680
[<c101c35d>] ? do_page_fault+0x14d/0x280
[<c104b8f6>] ? up_read+0x16/0x30
[<c103547c>] ? do_group_exit+0x3c/0xa0
[<c10354f3>] ? sys_exit_group+0x13/0x20
[<c1002d68>] ? sysenter_do_call+0x12/0x36

ps R running 0 12886 12884 0x00000000
c9189ca4 00200046 c1036db8 c9189c6c c1036f02 00200046 c1067e57 00000001
c15239dc c15239dc c15239dc 00000001 f6bfee60 00051f77 00000000 00000001
c1590000 c1592424 c15955c0 f6bfee64 f6bfecc0 c9189c80 c103716c f6bfecc0
Call Trace:
[<c1036db8>] ? _local_bh_enable+0x48/0xb0
[<c1036f02>] ? __do_softirq+0xe2/0x130
[<c1067e57>] ? handle_fasteoi_irq+0x87/0xc0
[<c103716c>] ? irq_exit+0x3c/0x80
[<c136f25c>] ? preempt_schedule_irq+0x2c/0x60
[<c1057c9c>] ? trace_hardirqs_on_caller+0x12c/0x180
[<c136f262>] preempt_schedule_irq+0x32/0x60
[<c1002cf2>] need_resched+0x1f/0x21
[<c102040a>] ? get_user_pages_fast+0x13a/0x170
[<c105beef>] ? get_futex_key+0xaf/0x1c0
[<c105c60c>] ? futex_wake+0x4c/0x110
[<c105de0d>] ? do_futex+0x21d/0xd00
[<c101bd86>] ? no_context+0x26/0x1a0
[<c102a013>] ? finish_task_switch+0x33/0xf0
[<c101bfbb>] ? __bad_area_nosemaphore+0xbb/0x180
[<c1058d8d>] ? __lock_acquire+0x39d/0x18e0
[<c1058d8d>] ? __lock_acquire+0x39d/0x18e0
[<c101c0c9>] ? __bad_area+0x29/0x50
[<c101c0da>] ? __bad_area+0x3a/0x50
[<c101c122>] ? bad_area_access_error+0x12/0x20
[<c1002e1c>] ? restore_all_notrace+0x0/0x18
[<c101c210>] ? do_page_fault+0x0/0x280
[<c1057c9c>] ? trace_hardirqs_on_caller+0x12c/0x180
[<c105e992>] ? sys_futex+0xa2/0x130
[<c101c210>] ? do_page_fault+0x0/0x280
[<c102fa68>] ? mm_release+0xa8/0xc0
[<c1033668>] ? exit_mm+0x18/0x110
[<c1065121>] ? acct_collect+0x131/0x180
[<c10353cb>] ? do_exit+0x60b/0x680
[<c101c35d>] ? do_page_fault+0x14d/0x280
[<c104b8f6>] ? up_read+0x16/0x30
[<c103547c>] ? do_group_exit+0x3c/0xa0
[<c10354f3>] ? sys_exit_group+0x13/0x20
[<c1002d68>] ? sysenter_do_call+0x12/0x36